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As a substitute for the Lowenthal method for the determination of tea tannin, a colorimetric method using Mitchell's ferrous tartrate reagent was investigated.The reagent consisted of FeSO4 . 7H2O (100 mg.) and Rochelle salt (500 mg.) in 100 ml. of water. Tea tannin and ferrous tartrate produced a reddish violet color, having a maximum absorption at 540 mμ, which was most intensive in the buffer solution of pH 7.5. The absorbance of the colored solution was kept constant for 4 hours, and a slight decrease in absorbance was observed with the temperature rise of 20◊. Since the individual catechins gave different coloration and intensity with ferrous tartrate, the amount of tea tannin adopted was calculated by the Lowenthal method.The recommended procedure is as follows: The sample solution containing tea tannin is prepared by extracting powdered tea (100 mg.) with water (100 ml.) in a boiling water bath for 30 minutes and filtering. Five ml. of the sample solution and the same quantity of the reagent are transferred into a 25-ml. volumetric flask and filled to the mark with Sorensen's phosphate buffer (pH 7.5). Then the absorbance is measured at 540 mμ against a blank solution substituting water for the reagent, and the amount of tea tannin is determined from the calibration curve.The variation coefficient of the determination was about 2 %.By the continuous variation method, it seemed that an Fe reacted with one molecule of gallic acid, two of (-)-epigallocatechin, and three of (-)-epicatechin respectively.

It was an well-known fact that the ordinary tea leaves contained about 5% of nitrogen in spring and about 3% in summer, but the reason why the depression of the nitrogen content occurred during these seasons has not yet been confirmed.With the purpose of solving this problem, some experiments were performed from 1952 to 1954, by comparing summer crops one of which harvested with regular plucking, the others had not been plucked or checked the flushing with MH-30 spraying in the preceeding season.In these experiments, the yield and nitrogen content of the regularly plucked tea bush decreased in the order of 1st, 2nd, and 3rd season, and tannin content varied in the reverse direction as many chemical analyses had shown previously.The bush unplucked in the preceeding season produced lower yield and the crop was poorer in nitrogen content and higher in tannin than the control. But, as the total amount of the chemical component harvested in the crop depended upon the yield, both nitrogen and tannin deprived were larger in the control.The bush which was checked its flushing by MH spraying in spring could not produce so rich leaves in nitrogen in summer as the control bush had produced in spring.The chemical analyses of mature leaves also showed the fact that the nitrogen did not seemed to be reserved in the leaves during the season when the flushing had been checked.As the results of 3-year's experiments, any proof for explaining the reason why the summer crop had lower nitrogen content was not obtained from the point of view of nitrogen absorbing. period from the tea root.

(1)ベーパークロマトグラフィによる茶葉タンニンの分離方法を設定するために,展開剤の選定,展開温度,展開剤の含水量について試驗した。展開されたタンニンは硫酸第二鐵によつて呈色させた. (2) その結果,茶葉タンiニンには供試した7種の溶剤の中,η一ブタノールの水飽和液が最も好結果を示した. (3) この方法によつて茶樹品種C-8, U-17,藪北の3種の茶葉タンニンの比較を行つたが,藪北は他の2種しとはタンニンの組成が違うことが分つた.

With the determination of tea tannin by the Lowenthal method and the colorimetric method using ferrous tartrate, the extraction rates of tannin in the green tea with several solvents, the temperature effect on the extraction of catechin fractions, and the reduction of tannin content by the filtration of infusion were investigated.The preparations of determining solutions were carried out as follows: in the Lowenthal method, 500 mg. of powdered tea was infused with ca. 70ml. of hot water for 90 min. and in the colorimetric method, 100 mg. of sample was treated in the same way for 30min. After cooling, both infusions were filled up to 100 ml. and filtered, then the tannin content in the filtrates was determined.Tea tannin, especially ester-type catechins, most of which consisted of (-)-epi-gallocatechin gallate, were less extractable in hot water than in aq. acetone and other organic solvents.The infused tannin content increased as the extraction temperature rose till 60°C., then reached almost a constant level.At a low temperature, the extraction rate of ester-type catechins was remarkably small, however, at a high temperature (over 80°C.)pyrogallol-type catechins seemed to be decomposed yielding gallic acid and (±)-gallocatechin.The tannin content was considerably lower in the first 20 ml. of filtrate through. several filter papers than in the succeding 20-40ml.

Data are presented showing the relationship of flavanolic constituents to tea leaves to the position in plucked shoots and to the stages of growth at various seasons. The results indicate that with the development of tea leaves, there is an increase of (–)-epigallocatechin and decrease of (–)-epigallocatechin gallate and (–)-epicatechin gallate. This suggested that past common data on the variation of tannin content is not always sufficient for such α subject.

In 1959, the experiment was designed by combining the gibberellin spraying and manuring, and each plot was given with the same treatment through all plucking seasons.The results of experiment were as follows: the growth rate of tea shoot sprayed with gibberellin was faster, and in 1st, 2nd, and 3rd plucking seasons the amount of growth per day were 3.9, 3.9, 6.3 mm. in the sprayed plots and 2.5, 2.2, 3.5 mm. in the unsprayed plots respectively.The number of shoot and number of leaf were not affected by gibberellin spraying, and both the sprayed and unsprayed shoot increased one leaf in 5 days in 1st season, 4 days in 2nd season and 3 days in 3rd season.The yield and weight of shoot were larger in the sprayed plots and the former of whole shoot and of P+3L showed an increase of 8% and 5% over the unsprayed plots.Of the chemical constituents, chlorophyll was reduced which coincided with the results of the preceding experiments, but total nitrogen, caffeine, tannin, and crude fibre contents showed no significant difference between the sprayed and the unsprayed.The qualities of black tea made with the sprayed leaves were better than those of the unsprayed, but the increase of the plucking cycle in a year could not be expected.

The tea leaves have been sampled during the rapid-growing period of the shoots. A slight difference of harvesting time had susceptible influence on the maturity of the leaves, as well as on their physical and chemical properties. As it is verey difficult to decide the best plucking time technically, the calculation of chemical constituents in the tea leaves is not available unless the maturity of the leaves is adjusted to a standard level. Then, the relation between the chemical constituents (tannin and total nitrogen) and the maturity of the leaves (indicated by the ratio of the bhanji shoot) was researched by a uniformity trial of sampling of the variety "Tamamidori" on the tea garden.In regard to the chemical constituents, no adjustment by the maturity of leaves was necessary for total nitrogen, as far as these surveys were concerned, but it is easily presumed that some adjustment to this constituent would be required if the sampling conditions would be varied. Whereas, an adjustment by the maturity of the leaves was necessary for tannin, even in the case.of these samples having such a narrow range of maturity.For the most reasonable tannin value, the data were adjusted by the maturity of the leaves at the best plucking time and the confident limits of the adjusted values were also calculated.The sample size for obtaining a balanced sampling to the accuracy of the chemical determination of tannin and total nitrogen was calculated; it was found to be satisfied with 10 samples when the maturity of the sample did not exceed so far from that of the leaves at the best plucking time.

The sample form of tea shoot for analyzing the chemical components was investigated. In the 1st plucking season 1956, the tea shoot of variety "Tamamidori"was plucked (P4-3L) in 10 plots on the same day, divided into individual leaves, and analyzed the total-N and tannin contents.By comparing the coefficient of variation (C. V.) of analytical values of respective. samples, it was proved that the C. V. of whole plucked shoot was the smallest among others, and if the tannin value was adjusted by the maturity of shoot (Debiraki-do), its C. V. was reduced less 1/2 than that of the unadjusted.In the case of day-after-day sampling of the same variety in the 3rd plucking season, the variation of chemical contents of individual leaves was complicated, but in the whole plucked shoot, not separated into parts, the total-N content kept a stable level during 20-70%o of Debiraki-do, and tannin content could be easily adjusted by a primary regression equation upon Debiraki-do.From the result of these two experiments, any advantage could not be recognized by dividing the shoot into individual leaves.The ratios of chemical content of individual leaves to whole shoot were as follows: the 1st leaf '117 (total-N), 125 (tannin) ; the 2nd leaf 104, 108 ; the 3rd leaf 93, 89, and these figures were nearly constant in spite of the maturity of shoot and the plucking season.